Makefile: prune quilt source files for cscope

Both quilt, to apply patches, and cscope, to navigate in the code, are
useful tools. Make sure source files that quilt saves when applying
patches are not taken into account when building the cscope database.

Link: https://lore.kernel.org/qemu-devel/20250630172048.519182-1-clg@redhat.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

Makefile

@@ -227,6 +227,7 @@ distclean: clean recurse-distclean
 	rm -Rf .sdk qemu-bundle
 
 find-src-path = find "$(SRC_PATH)" -path "$(SRC_PATH)/meson" -prune -o \
+	-path "$(SRC_PATH)/.pc" -prune -o \
 	-type l -prune -o \( -name "*.[chsS]" -o -name "*.[ch].inc" \)
 
 .PHONY: ctags